Hydrogen exchange methods are being applied to the study of structure, structure change, and structural dynamics in hemoglobin, elastin, rhodopsin, and DNA. In hemoglobin, a particular high energy structure change is being characterized with respect to its free energy and the way this corresponds to the total allosteric energy of the hemoglobin molecule. The degree and stability of H-binding in insoluble elastin is being measured. The correlation between rhodopsin structure when membrane-bound and when solubilized in octyl glucoside is being determined. A stopped-flow method is being applied to study breathing in DNA. In other work, the physical chemistry of sickle hemoglobin gelation is being studied and various inhibitors of the gelation process are being tested.